Chemistry for Kids: Elements - The Noble Gases Elements for Kids Noble Gases The noble gases are a group of elements in the periodic table. They are located to the far right of the periodic table and make up the eighteenth column. Elements in the noble gas family have atoms with a full outer shell of electrons. They are also called the inert gases. What elements are noble gases? The elements that make up the family of noble gases include helium , neon , argon , krypton, xenon, and radon. What are the similar properties of noble gases? Noble gases share many similar properties including: A full outer shell of electrons. Helium has two electrons in its outer shell and the rest have eight electrons. Because of their full outer shells, they are very inert and stable. This means they don't tend to react with other elements to form compounds. They are gases under standard conditions. They are colorless and odorless. Their melting and boiling points are close together giving them a very narrow liquid range. Abundance Helium is the second most abundant element in the universe after hydrogen. Helium makes up about 24% of the mass of the elements in the universe.

Neon is the fifth most abundant and argon is the eleventh. On Earth, the noble gases are fairly rare with the exception of argon. Argon makes up just under 1% of the Earth's atmosphere, making it the third most abundant gas in the atmosphere after nitrogen and oxygen. Interesting Facts about Noble Gases Because helium is non-flammable it is much safer to use in balloons than hydrogen. Krypton gets its name from the Greek word "kryptos" meaning "the hidden one." Many of the noble gases were either discovered or isolated by Scottish chemist Sir William Ramsay. Helium has the lowest melting and boiling points of any substance. All of the noble gases except for radon have stable isotopes. Neon signs do not use just neon gas, but a mixture of different noble gases and other elements to create bright lights of different colors. Noble gases are often used to create a safe or inert atmosphere due to their stable nature.

Xenon gets its name from the Greek word "xenos" which means "stranger or foreigner." More on the Elements and the Periodic Table Noble gas - CreationWiki, the encyclopedia of creation science Noble gas Uuo Noble Gases or rare gases are very stable, nearly chemically inert elements, [1] that are in a gaseous state at room temperature. A Noble Gas is a gas that's outer shell is full. All of the outer electron shells of the Noble Gases are filled with 8 electrons except for Helium which has only 2 in the first shell. The Noble Gases were discovered in 1886. [1] Originally they were called inert gases because people thought that they were nonreactive. That has since been proven wrong. In 1962 the British chemist Neil Bartlett synthesised the first group 0 compound, xenon hexafluoroplatinate. [2] Since then, chemists have been able to create compounds with three of the Noble Gases (xenon, krypton, and radon). [3] The electron configurations of the Noble Gases are very stable and usually very resistant to any change.

Contents 6 Related References The Six Noble Gases Helium has an atomic number of 2, the Atomic symbol is He, and the atomic mass is 4.002602g/mol. The name helium comes from Helios which means sun in Greek. It was first discovered by Sir William Ramsay in 1895. Neon has an atomic number of 10, the Atomic Symbol Ne, and the atomic mass of 20.180g/mol. Its name comes from the greek word Neos which means new. It was discovered by Sir William Ramsay in 1898 Argon has an Atomic Number of 18, the Atomic Symbol Ar, and the Atomic Mass of 39.948g/mol. The name comes from the Greek word Argon which means inactive. It was discovered by Sir William Ramsay in 1894. Krypton has an Atomic Number of 36, the Atomic Symbol Kr, and the Atomic Mass of 83.80g/mol. Its name comes from the Greek word kryptos which means hidden. It was discovered in 1898 by Sir William Ramsay.

Xenon has an Atomic Number of 54, the Atomic Symbol Xe, and the Atomic Mass of 131.290g/mol. The word Xenon comes from the Greek word xenon which means stranger it was discovered by Sir William Ramsay in 1898. Radon has an Atomic Number of 86, the Atomic Symbol Rn, and the Atomic Mass of 222.018g/mol. The name comes from the word radium and it was discovered in 1898 by Fredrich Ernst Dorn.* [2] Periodic table of elements with the Noble Gases illustrated with black border. Uses of Noble Gases Even though Noble Gases usually do not combine with other elements they have many different uses. Have you ever seen the signs with neon lights that flash and say words on them? Those signs are made using neon and argon. Helium is used for balloons, blimps, and airships because it is lighter than air so they will float, and is less flammable than hydrogen. Krypton is used for lighting, Xenon is used in powerful lamps and bubble chambers. Radon is used for the treatment of cancer.

[3] Electron Configurations The Elements: Noble Gases The Noble Gases With a name taken from the Greek helios for "sun", helium is the second lightest and second most abundant gas in the known universe (hydrogen being number one). Because of its scarcity in our atmosphere its existence was not suspected until spectroscopic measurements revealed an unknown element present in the sun. The discovery of helium is generally credited to Janssen and Lockyear in 1868. As no helium compounds are known, this family of gases was once thought to be inert. In 1962 the first noble gas compound was prepared with xenon (see below). Still, helium only occurs in uncombined form and must either be extracted from the atmosphere by liquefaction of air or separated from deposits of natural gas. It is thought that some of the terrestrial helium is the product of the alpha decay of radioactive isotopes beneath the crust. Helium is the only known element which cannot be converted to a solid simply by cooling. It has 98% the lifting power of hydrogen with none of the Hindenburg-type drawbacks, and is still used today in airships.

Additional Information About Helium The fourth most abundant element in the known universe, neon was discovered in 1898 by Ramsay and Travers. Its name is taken from the Greek neos or "new". This is perhaps the best known noble gas because of its use in so-called "neon" lights (many of which actually contain other gases) and is relatively plentiful in the earth's atmosphere (fifth in abundance, following carbon dioxide). No stable compounds of neon are known to date. The gas is extracted from air by liquefaction. Additional Information About Neon Argon is third in abundance in the earth's atmosphere (about 1% by volume). Rayleigh and Ramsay isolated and identified the gas in 1894. Like the rest of the noble gases, it is colorless, tasteless and odorless. The name for argon is taken from the Greek argos for "inactive". For years argon has been used in ordinary incandescent light bulbs to replace the oxygen that would otherwise shorten the lifetime of the filament. It is used in some types of welding where active atmospheric gases would interfere with the process.

Argon is also used in various types of "black lights" or UV lamps since excitation of the gas produces a significant amount of ultraviolet radiation. A few curious compounds have been made with argon but they are not very stable. Additional Information About Argon Named from the Greek kryptos or "hidden", krypton is neither green nor a solid material that can defeat Superman. Rather it is another noble gas discovered in 1898 by Ramsay and Travers. It ranks sixth in abundance in the atmosphere. Krypton gas is used in various kinds of lights, from small bright flashlight bulbs to special strobe lights for airport runways. As with the other noble gases, krypton is isolated from the air by liquefaction. One of the naturally occurring non-radioactive isotopes of krypton, Kr-86 (17.3%) is used as the basis for the current international definition of the meter. One meter is 1,650,762.73 wavelengths of the red-orange spectral line of krypton-86.

Additional Information About Krypton Also discovered by Ramsay and Travers in 1898, xenon (from the Greek xenos for "strange") is the rarest of the stable noble gases in the air. It is still recovered by liquefaction techniques and is widely used in strobe lamps. In 1962 the first noble gas compound was produced by Neil Bartlett, combining xenon, platinum and fluorine. It is now possible to produce xenon compounds in which the oxidation states range from +2 to +8(!). Additional Information About Xenon Discovered in 1900 by Friedrich Dorn, radon is a radioactive noble gas now regarded as a potential health hazard in some homes. It also has medical applications for cancer treatment. Its original name was to be niton for "shining" but it was eventually named as a derivative of radium. Radon is found in underground deposits where is it produced by uranium and radium decay. Radon fluoride (RnF) has been produced and the element glows with a yellow light in the solid state.

It's Elemental - The Element Krypton It's Elemental Melting Point: 115.79 K (-157.36°C or -251.25°F) Boiling Point: 119.93 K (-153.22°C or -243.80°F) Density: 0.003733 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 4 Group Number: 18 Group Name: Noble Gas What's in a name? From the Greek word for hidden, kryptos. Say what? Krypton is pronounced as KRIP-ton. History and Uses: Krypton was discovered on May 30, 1898 by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, while studying liquefied air. Small amounts of liquid krypton remained behind after the more volatile components of liquid air had boiled away. The earth's atmosphere is about 0.0001% krypton. The high cost of obtaining krypton from the air has limited its practical applications.

Krypton is used in some types of photographic flashes used in high speed photography. Some fluorescent light bulbs are filled with a mixture of krypton and argon gases. Krypton gas is also combined with other gases to make luminous signs that glow with a greenish-yellow light. In 1960, the length of the meter was defined in terms of the orange-red spectral line of krypton-86, an isotope of krypton. Once thought to be completely inert, krypton is known to form a few compounds. Krypton difluoride (KrF2) is the easiest krypton compound to make and gram amounts of it have been produced. For those that are curious, pictures of krypton gas and krypton plasma can be found in the Questions and Answers section of this site.

Estimated Crustal Abundance: 1×10-4 milligrams per kilogram Estimated Oceanic Abundance: 2.1×10-4 milligrams per liter Number of Stable Isotopes: 5 ( View all isotope data ) Ionization Energy: 14.000 eV Noble Gases | IAS Noble Gases Tweet on Twitter The noble gases are a group of elements in the periodic table . They are located to the far right of the periodic table and make up the eighteenth column. Elements in the noble gas family have atoms with a full outer shell of electrons. They are also called the inert gases. The elements that make up the family of noble gases include helium, neon, argon, krypton, xenon, and radon. What are the similar properties of noble gases? Noble gases share many similar properties including: A full outer shell of electrons. Helium has two electrons in its outer shell and the rest have eight electrons. Because of their full outer shells, they are very inert and stable. This means they don’t tend to react with other elements to form compounds. They are gases under standard conditions. They are colourless and odourless.

Their melting and boiling points are close together giving them a very narrow liquid range. Abundance Helium is the second most abundant element in the universe after hydrogen. Helium makes up about 24% of the mass of the elements in the universe . Neon is the fifth most abundant and argon is the eleventh.On Earth , the noble gases are fairly rare with the exception of argon. Argon makes up just under 1% of the Earth’s atmosphere, making it the third most abundant gas in the atmosphere after nitrogen and oxygen. Also Read: Halogens Radon Radon is the heaviest of the noble gases and was discovered due to the decay of radium. Uranium and radium are naturally present in rock and soil. Radon can get concentrated in unventilated indoor areas built into the soil such as basements. Due to its colourless property, it can’t be detected easily. Radon accumulating indoors is a serious health hazard. This is because when radon breaks down, it produces charged particles that become a part of the dust, and are dangerous when inhaled. This hazard is also posed in structures constructed from certain granites. Radon does have its uses too.

Radon-222, the most common isotope, is used in the treatment of malignant tumours. Interesting Facts about Noble Gases Because helium is non-flammable it is much safer to use in balloons than hydrogen. Krypton gets its name from the Greek word “kryptos” meaning “the hidden one.” Many of the noble gases were either discovered or isolated by Scottish chemist Sir William Ramsay. Helium has the lowest melting and boiling points of any substance. All of the noble gases except for radon have stable isotopes. Neon signs do not use just neon gas, but a mixture of different noble gases and other elements to create bright lights of different colours. Noble gases are often used to create a safe or inert atmosphere due to their stable nature. Xenon gets its name from the Greek word “xenos” which means “stranger or foreigner.” Sir William Ramsay (1852-1916) was a British chemist, and was the first to successfully isolate all of the noble gases, except radon. He also discovered 4 of them, namely neon, argon, krypton, and xenon.

Pierre Janssen discovered helium in 1868 during a solar eclipse in the spectrum of the corona of the sun . However, Ramsay was the first to isolate it. Ramsay and the British physicist Lord Raleigh found that nitrogen removed from the atmosphere was denser than nitrogen formed by the decomposition of ammonium nitrate. This led to the discovery of argon in 1894. Helium was discovered by Janssen in 1895. Through the attempts of Ramsay and his assistant Morris Travers, krypton, neon and xenon were found from the atmosphere by fractional distillation. Radon was discovered by a German chemist, Friedrich Ernst Dorn in 1900. Krypton Krypton Krypton is a noble-gas, which has atomic number 18.Its name comes from the greek word for hidden, Kryptos. Krypton is Discovered Krypton was discovered by Sir William Ramsay, who was scottish, and Morris M. Travers, who was english, while they were studying liquefied air. Krypton and Other Elements Krypton mixes with Argon as a source of energy saving fluorescent gas lamps.

Tpgether with Xenon, it creates a birghter light which is used to allow higher temperatures. Krypton in the World In the atmosphere, krypton's concentration is 1 ppm. The amount of it in space is uncertain, but the first measurements suggested that it was an overabundance. Curiosities Krypton can be used to discover the presence of secret nuclear weapons and its research facilities. Also, krypton-fluorine lasers produce pulses with 500 times the power of the US. Numbers Everywhere Crustal Abundance: 1×10-4 milligrams per kilogram Oceanic Abundance: 2.1×10-4 milligrams per liter Stable Isotopes: 5 Ionization energy: 14.000 eV Oxidation Sate: 0 State Krypton is a colorless and odorless gas, which is inert to everything but fluorine. One of the rarest gases in the earth's atmosphere. Krypton 86 Krypton 86 is an isotope that has a line in its atomic spectrum which is now the standard measure of length.

One meter is exactly 1,650,763.73 wavelengths of this line. Search BBC Science - The periodic table: how elements get their names The periodic table: how elements get their names By Christopher Brooks BBC Scotland Most people could name many of the elements, but how many of us know how they got those names? Each of the 115 known chemical elements was discovered over the last few thousand years, from before recorded history began to the nuclear laboratories of the 21st century. British scientists and the elements Humphry Davy discovered nine elements using electrolysis - the splitting up of compounds into elements by applying electricity. William Ramsay discovered a new group of unreactive elements using spectroscopy , now called the noble gases. William Crookes identified helium for the first time, and also discovered thallium . Their chosen names were influenced by an ever changing mix of language, culture and our understanding of chemistry. So how did they get these names? And why do they end in -ium? Ancient Elements Several elements' names have Anglo-Saxon language origins, including gold, iron, copper and silver. These metals were known long before they got these names, however.

Gold can be found in its pure form in nature and although iron is usually found in ores which require smelting, the earliest known iron artefacts, from 3500 BCE, derive from purer metal from meteorites. The Latin names of these elements are commemorated in their atomic symbols, Au (aurum) for gold and Fe (ferrum) for iron. The Romans began the practise of element names ending in "-um," with Victorian scientists continuing the trend. Meteoric iron was used by humans before smelting of iron ores was invented. Element of uncertainty Since 1947, the International Union of Pure and Applied Chemistry ( IUPAC ) has had the responsibility for approving elements' names, and deciding the single internationally recognised symbol for each element. Before this, there were multiple historical occasions of elements being given several names, usually due to simultaneous discovery or uncertainty over a discovery. The name of element 41 was not agreed for 150 years. It was called columbium in America and niobium in Europe until IUPAC finally decided the official name would be niobium in 1949.

Dr Fabienne Meyers, Associate Director of IUPAC, explains the current naming process : To start with, "the discoverers are invited to propose a name and a symbol." "For linguistic consistency, the recommended practice is that all new elements should end in '-ium'," she adds. The sake of naming an element is essentially to avoid confusion.” End Quote Dr Fabienne Meyers Associate Direcor, IUPAC "Since the sake of naming an element is essentially to avoid confusion, it is important to ensure that the proposed name is unique and has not been used earlier even unofficially or temporarily for a different element." "After examination and acceptance by the division - which includes a public review period of five months - the name and symbol are then submitted to the IUPAC Council for approval." The name is then published in the scientific journal Pure and Applied Chemistry . Actinium to zirconium A common source of names both now and historically, over a quarter of the elements are named after a place, often where they were discovered or synthesised. These places range in size from continents (europium) and countries (americium, francium, polonium) to the the Scottish village Strontian (strontium).

Because of the great wealth of discoveries made there, four elements are named after the Swedish mining village, Ytterby (ytterbium, yttrium, erbium and terbium). There is just one element that wasn't first discovered on Earth, and it too is named after its place of the discovery - helium, from the Greek word for Sun, helios. Myth and legend Dmitri Mendeleev published the periodic table in its modern form. About a dozen elements take their name directly from legends, including titanium, arsenic and tantalum. Nickel and cobalt are named after 'devil' and 'kobold', from the Germanic folk belief that malign creatures snuck into mines to replace valuable and similar-looking copper and silver ores with these less valuable ones. In 1949 the artificial element Promethium was named after Prometheus, the man in Greek legend punished with eternal torture for stealing fire from the gods, as a reference to the great difficulty and sacrifice needed to synthesise new elements. Eponymous elements Modestly, no discoverer has ever named an element after him or herself, but several scientists have been honoured by having elements named after them.

These include curium , einsteinium and fermium . Seaborgium, named after American chemist Glenn Seaborg , was the first element to be named after a living scientist. There is also mendelevium, named after Dmitri Mendeleev , the Russian scientist who established the first periodic table in 1869, and fitted the known elements into their places in the table based on their properties. Elemental techniques Sample of chlorine created by Humphry Davy in 1810. It is named after the Greek word for green. Fifty elements were discovered in the 19th Century, the greatest number of any century. By comparison, twenty nine elements were discovered in the 20th Century, and five new ones have been synthesised so far in the 21st. Frank James, Professor of the History of Science at The Royal Institution in London, where several elements were discovered, says that the contribution of British scientists was very important.

"Using electro-chemical methods, Humphry Davy either isolated or demonstrated the elemental nature of a total of nine chemical elements naming most of them in the process, such as sodium, potassium and chlorine." British scientist William Ramsay used a powerful new technique, spectroscopy , to discover the noble gases, a group of elements which had evaded discovery due to their lack of reactivity. He used Greek words to name neon (new), xenon (stranger), krypton (hidden), and argon (inactive). Colours and sense Colours are a name source for nine elements. Each element can be identified by the colours it emits using spectroscopy, and several elements are named after the brightest colour they emit, including indium and rubidium. WATCH: Brian Cox explains how the chemical elements are created within stars Visible traits are a major source of names, but the other senses are represented too: osmium and bromine are named for their smell, and aluminium is named after the Latin word for the bitter tasting chemical in which it was first discovered, alum.

Ununpentium onwards The newest element to be experimentally confirmed , element 115, will be called ununpentium until an official name is decided, and 114 (Flerovium) and 116 (Livermorium) were named in 2012. IUPAC's Dr Meyers explains that although all recent elements have been named after people and places, "a mythological concept or character, a mineral or a property of the element could also be used as the root for an acceptable name." And with no shortage of eminent scientists and important centres of science as inspiration, new names will always retain an element of surprise. More on This Story The Elements of Group 18 (The Noble Gases) 22.6 The Elements of Group 18 (The Noble Gases) Learning Objective To understand the trends in properties and reactivity of the group 18 elements: the noble gases. The noble gases were all isolated for the first time within a period of only five years at the end of the 19th century.

Their very existence was not suspected until the 18th century, when early work on the composition of air suggested that it contained small amounts of gases in addition to oxygen, nitrogen, carbon dioxide, and water vapor. Helium was the first of the noble gases to be identified, when the existence of this previously unknown element on the sun was demonstrated by new spectral lines seen during a solar eclipse in 1868. (For more information on spectroscopy, see Chapter 6 "The Structure of Atoms" .) Actual samples of helium were not obtained until almost 30 years later, however. In the 1890s, the English physicist J. W. Strutt (Lord Rayleigh) carefully measured the density of the gas that remained after he had removed all O2, CO2, and water vapor from air and showed that this residual gas was slightly denser than pure N2 obtained by the thermal decomposition of ammonium nitrite. In 1894, he and the Scottish chemist William Ramsay announced the isolation of a new “substance” (not necessarily a new element) from the residual nitrogen gas.

Because they could not force this substance to decompose or react with anything, they named it argon (Ar), from the Greek argos, meaning “lazy.” Because the measured molar mass of argon was 39.9 g/mol, Ramsay speculated that it was a member of a new group of elements located on the right side of the periodic table between the halogens and the alkali metals. He also suggested that these elements should have a preferred valence of 0, intermediate between the +1 of the alkali metals and the −1 of the halogens. J. W. Strutt (Lord Rayleigh) (1842–1919) Lord Rayleigh was one of the few members of British higher nobility to be recognized as an outstanding scientist. Throughout his youth, his education was repeatedly interrupted by his frail health, and he was not expected to reach maturity. In 1861 he entered Trinity College, Cambridge, where he excelled at mathematics. A severe attack of rheumatic fever took him abroad, but in 1873 he succeeded to the barony and was compelled to devote his time to the management of his estates.

After leaving the entire management to his younger brother, Lord Rayleigh was able to devote his time to science. He was a recipient of honorary science and law degrees from Cambridge University. Sir William Ramsay (1852–1916) Born and educated in Glasgow, Scotland, Ramsay was expected to study for the Calvanist ministry. Instead, he became interested in chemistry while reading about the manufacture of gunpowder. Ramsay earned his PhD in organic chemistry at the University of Tübingen in Germany in 1872. When he returned to England, his interests turned first to physical chemistry and then to inorganic chemistry. He is best known for his work on the oxides of nitrogen and for the discovery of the noble gases with Lord Rayleigh. In 1895, Ramsey was able to obtain a terrestrial sample of helium for the first time.

Then, in a single year (1898), he discovered the next three noble gases: krypton (Kr), from the Greek kryptos, meaning “hidden,” was identified by its orange and green emission lines; neon (Ne), from the Greek neos, meaning “new,” had bright red emission lines; and xenon (Xe), from the Greek xenos, meaning “strange,” had deep blue emission lines. The last noble gas was discovered in 1900 by the German chemist Friedrich Dorn, who was investigating radioactivity in the air around the newly discovered radioactive elements radium and polonium. The element was named radon (Rn), and Ramsay succeeded in obtaining enough radon in 1908 to measure its density (and thus its atomic mass). For their discovery of the noble gases, Rayleigh was awarded the Nobel Prize in Physics and Ramsay the Nobel Prize in Chemistry in 1904. Because helium has the lowest boiling point of any substance known (4.2 K), it is used primarily as a cryogenic liquid.

Helium and argon are both much less soluble in water (and therefore in blood) than N2, so scuba divers often use gas mixtures that contain these gases, rather than N2, to minimize the likelihood of the “bends,” the painful and potentially fatal formation of bubbles of N2(g) that can occur when a diver returns to the surface too rapidly. Preparation and General Properties of the Group 18 Elements Fractional distillation of liquid air is the only source of all the noble gases except helium. Although helium is the second most abundant element in the universe (after hydrogen), the helium originally present in Earth’s atmosphere was lost into space long ago because of its low molecular mass and resulting high mean velocity. Natural gas often contains relatively high concentrations of helium (up to 7%), however, and it is the only practical terrestrial source. The elements of group 18 all have closed-shell valence electron configurations, either ns2np6 or 1s2 for He. Consistent with periodic trends in atomic properties, these elements have high ionization energies that decrease smoothly down the group.

From their electron affinities, the data in Table 22.7 "Selected Properties of the Group 18 Elements" indicate that the noble gases are unlikely to form compounds in negative oxidation states. A potent oxidant is needed to oxidize noble gases and form compounds in positive oxidation states. Like the heavier halogens, xenon and perhaps krypton should form covalent compounds with F, O, and possibly Cl, in which they have even formal oxidation states (+2, +4, +6, and possibly +8). These predictions actually summarize the chemistry observed for these elements. Table 22.7 Selected Properties of the Group 18 Elements Property List of Noble Gases | eHow List of Noble Gases neon sign image by pearlguy from Fotolia.com The six noble gases are all found in group 18 of the periodic table. Noble gases are different from other elements because they have a full set of electrons in their outer shell. Most gases have too few or too many. This complete electron shell makes noble gases very stable, a fact that once saw them referred to as "inert gases." However, some of the noble gases are now known to take part in chemical reactions.

Helium Helium has an atomic number of 2 and is represented by the symbol He. The gas was discovered in 1895, but, according to the BBC website, its existence had been previously proposed by Pierre Jules Cesar and Sir Joseph Norman Lockyer. The two men that named the gas "helium" after the Greek word for sun. Helium is often used in balloons due to its lighter than air properties. It is also used in deep sea diving equipment to dilute a diver's oxygen supply. Neon Neon has an atomic number of 10 and the symbol Ne. It was discovered in 1898 by two British chemists, William Ramsay and Morris W. Travers, and named after the Greek word for new, "neos." Neon is often used in lighting and fluorescent signs. The gas itself is colorless but glows in an electric discharge. Argon Argon has an atomic number of 18 and the symbol Ar. It was isolated in 1894 by Lord Rayleigh and William Ramsay, becoming the first of the noble gases to be discovered. The stable nature of the gas earned it the name "argon," the Greek word for inert.

According to the Royal Society of Chemistry website, "Argon is widely used to provide an inert atmosphere for high-temperature metallurgical processes." Like neon, it is also used in lighting. Krypton Krypton is represented by the symbol Kr and has an atomic number of 36. Krypton was discovered in 1898 by William Ramsay and Morris W. Travers, just a few weeks before they discovered neon. It was named after the Greek word "kryptos," meaning hidden. The gas is used in fluorescent lighting and in various types of photographic flash bulbs. Xenon Xenon has an atomic number of 54 and the symbol Xe. It was discovered by Ramsey and Travers in 1898, shortly after their discovery of neon and krypton, and named after the Greek word for stranger. Xenon is found naturally in the atmosphere, but only in minute quantities. According to the PeriodicTable.org website, xenon is used in photographic flashes, general anesthetic and stroboscopic, bactericidal, and laser-pumping lamps. Radon Radon, the last noble gas to be isolated, has an atomic number of 86 and the symbol Rn.

It was initially observed in the 1890s before being isolated by Friedrich Ernst Dorn in 1900. It was properly classified in 1908 by William Ramsay. Radon is colorless, odorless, tasteless and, unlike the other noble gases, radioactive. It occurs naturally from decaying radium and is considered hazardous due to its radioactivity. It is used in radiotherapy for the treatment of cancer. Noble gases facts, information, pictures | Encyclopedia.com articles about Noble gases Isolation of the Noble Gases HELIUM. Helium is an unusual element in many respects—not least because it is the only element to have first been identified in the Solar System before it was discovered on Earth. This is significant, because the elements on Earth are the same as those found in space: thus, it is more than just an attempt at sounding poetic when scientists say that humans, as well as the world around them, are made from "the stuff of stars." In 1868, a French astronomer named Pierre Janssen (1824-1907) was in India to observe a total solar eclipse.

To aid him in his observations, he used a spectroscope, an instrument for analyzing the spectrum of light emitted by an object. What Janssen's spectroscope showed was surprising: a yellow line in the spectrum, never seen before, which seemed to indicate the presence of a previously undiscovered element. Janssen called it "helium" after the Greek god Helios, or Apollo, whom the ancients associated with the Sun . Janssen shared his findings with English astronomer Sir Joseph Lockyer (1836-1920), who had a worldwide reputation for his work in analyzing light waves. Lockyer, too, believed that what Janssen had seen was a new element, and a few months later, he observed the same unusual spectral lines. At that time, the spectroscope was still a new invention, and many members of the worldwide scientific community doubted its usefulness, and therefore, in spite of Lockyer's reputation, they questioned the existence of this "new" element. Yet during their lifetimes, Janssen and Lockyer were proven correct. NEON, ARGON, KRYPTON, AND XENON. They had to wait a quarter century, however.

In 1893, English chemist Sir William Ramsay (1852-1916) became intrigued by the presence of a mysterious gas bubble left over when nitrogen from the atmosphere was combined with oxygen. This was a phenomenon that had also been noted by English physicist Henry Cavendish (1731-1810) more than a century before, but Cavendish could offer no explanation. Ramsay, on the other hand, had the benefit of observations made by English physicist John William Strutt, Lord Rayleigh (1842-1919). Up to that time, scientists believed that air consisted only of oxygen, carbon dioxide, and water vapor. However, Rayleigh had noticed that when nitrogen was extracted from air after a process of removing those other components, it had a slightly higher density than nitrogen prepared from a chemical reaction. In light of his own observations, Ramsay concluded that whereas nitrogen obtained from chemical reactions was pure, the nitrogen extracted from air contained trace amounts of an unknown gas. Ramsay was wrong in only one respect: hidden with the nitrogen was not one gas, but five.

In order to isolate these gases, Ramsay and Rayleigh subjected air to a combination of high pressure and low temperature, allowing the various gases to boil off at different temperatures. One of the gases was helium—the first confirmation that the element existed on Earth—but the other four gases were previously unknown. The Greek roots of the names given to the four gases reflected scientists' wonder at discovering these hard-to-find elements: neos (new), argos (in active), kryptos (hidden), and xenon (stranger). RADON. Inspired by the studies of Polish-French physicist and chemist Marie Curie (1867-1934) regarding the element radium and the phenomenon of radioactivity (she discovered the element, and coined the latter term), German physicist Friedrich Dorn (1848-1916) became fascinated with radium. Studying the element, he discovered that it emitted a radioactive gas, which he dubbed "radium emanation." Eventually, however, he realized that what was being produced was a new element. This was the first clear proof that one element could become another through the process of radioactive decay.

Ramsay, who along with Rayleigh had received the Nobel Prize in 1904 for his work on the noble gases, was able to map the new element's spectral lines and determine its density and atomic mass. A few years later, in 1918, another scientist named C. Schmidt gave it the name "radon." Due to its behavior and the configuration of its electrons, chemists classified radon among what they continued to call the "inert gases" for another half-century—until Bartlett's preparation of xenon compounds in 1962. Presence of the Rare Gases on Earth IN THE ATMOSPHERE. Though the rare gases are found in minerals and meteorites on Earth, their greatest presence is in the planet's atmosphere. It is believed that they were released into the air long ago as a by-product of decay on the part of radioactive materials in the Earth's crust. Within the atmosphere, argon is the most "abundant"—in comparative terms, given the fact that the "rare gases" are, by definition, rare.

Nitrogen makes up about 78% of Earth's atmosphere and oxygen 21%, meaning that these two elements constitute fully 99% of the air above the Earth. Argon ranks a distant third, with 0.93%. The remaining 0.07% is made up on water vapor, carbon dioxide, ozone (O3), and traces of the noble gases. These are present in such small quantities that the figures for them are not typically presented as percentages, but rather in terms of parts per million (ppm). The concentrations of neon, helium, krypton, and xenon in the atmosphere are 18, 5, 1, and 0.09 ppm respectively. IN THE SOIL. Radon in the atmosphere is virtually negligible, which is a fortunate thing, in light of its radioactive qualities. Few Americans, in fact, even knew of its existence until 1988, when the United States Environmental Protection Agency (EPA) released a report estimating that some ten million American homes had potentially harmful radon levels. This set off a scare, and during the late 1980s and 1990s, sales of home radon detectors boomed.

Meanwhile, the federal government increased concerns with additional reports, advising people to seal their basements and ventilate their homes if radon exceeded certain levels. A number of scientists have disputed the government's claims, yet some regions of the United States appear to be at relatively high risk due to the presence of radon in the soil. The element seems to be most plentiful in soils containing high concentrations of uranium. If radon is present in a home that has been weather-sealed to improve the efficiency of heating and cooling systems, it is indeed potentially dangerous to the residents. Chinese scientists in the 1960s made an interesting discovery regarding radon and its application to seismography, or the area of the earth sciences devoted to studying and predicting earthquakes. Radon levels in groundwater, the Chinese reports showed, rise considerably just before an earthquake. Since then, the Chinese have monitored radon concentrations in water, and used this data to predict earthquakes. EXTRACTING RARE GASES.

Radon, in fact, is not the only rare gas that can be obtained as the result of radioactive decay: in 1903, Ramsay and British chemist Frederick Soddy (1877-1956) showed that the breakdown of either uranium or radium results in the production of helium atoms (beta particles). A few years later, English physicist Ernest Rutherford (1871-1937) demonstrated that radiation carrying a positive electrical charge (alpha rays) was actually a stream of helium atoms stripped of an electron. Many of the noble gases are extracted by liquefying air—that is, by reducing it to temperatures at which it assumes the properties of a liquid rather than a gas. By controlling temperatures in the liquefied air, it is possible to reach the boiling point for a particular noble gas and thereby extract it, much as was done when these gases were first isolated in the 1890s. THE UNIQUE SITUATION OF HELIUM. Helium is remarkable, in that it only liquefies at a temperature of −457.6°F (−272°C), just above absolute zero.

Absolute zero is the temperature at which the motion of atoms or molecules comes to a virtual stop, but the motion of helium atoms never completely ceases. In order to liquefy it, in fact, even at those low temperatures, it must be subjected to pressures many times that exerted by Earth's atmosphere. Given these facts, it is difficult to extract helium from air. More often, it is obtained from natural gas wells, where it is present in relatively large concentrations—between 1% and 7% of the natural gas. The majority of the Earth's helium supply belongs to the United States, where the greatest abundance of helium-supplying wells are in Texas , Oklahoma , and Kansas . During World War II , the United States took advantage of this supply of relatively inexpensive helium to provide buoyancy for a fleet of airships used for reconnaissance. There is one place with an abundant supply of helium, but there are no plans for a mining expedition any time soon. That place is the Sun, where the nuclear fusion of hydrogen atoms creates helium. Indeed, helium seems to be the most plentiful element of all, after hydrogen, constituting 23% of the total mass of the universe. Why, then, is it so difficult to obtain on Earth?

Most likely because it is so light in comparison to air; it simply floats off into space. Applications for the Noble Gases RADON, ARGON, KRYPTON, AND XENON. Though radon is known primarily for the hazards it poses to human life and well-being, it has useful applications. As noted above, its presence in groundwater appears to provide a possible means of predicting earthquakes. In addition, it is used for detecting leaks, measuring flow rates, and inspecting metal welds. One interesting use of argon and, in particular, the stable isotope argon-40, is in dating techniques used by geologists, paleontologists, and other scientists studying the distant past. When volcanic rocks are subjected to extremely high temperatures, they release argon, and as the rocks cool, argon-40 accumulates. Because argon-40 is formed by the radioactive decay of a potassium isotope, potassium-40, the amount of argon-40 that forms is proportional to the rate of decay for potassium-40.

The latter has a half-life of 1.3 billion years, meaning that it takes 1.3 billion years for half the potassium-40 originally present to be converted to argon-40. Using argon-40, paleontologists have been able to estimate the age of volcanic layers above and below fossil and artifact remains in east Africa. Krypton has a number of specialized applications—for instance, it is mixed with argon and used in the manufacture of windows with a high level of thermal efficiency. Used in lasers, it is often mixed with a halogen such as fluorine. In addition, it is also sometimes used in halogen sealed-beam headlights. Many fans of Superman, no doubt, were disappointed at some point in their lives to discover that there is no such thing as "kryptonite," the fictional element that caused the Man of Steel to lose his legendary strength. Yet krypton—the real thing—has applications that are literally out of this world. In the development of fuel for space exploration, krypton is in competition with its sister element, xenon. Xenon offers better performance, but costs about ten times more to produce; thus krypton has become more attractive as a fuel for space flight.

In addition to its potential as a space fuel, xenon is used in arc lamps for motion-picture film projection, in high-pressure ultraviolet radiation lamps, and in specialized flashbulbs used by photographers. One particular isotope of xenon is utilized for tracing the movement of sands along a coastline. Xenon is also applied in high-energy physics for detecting nuclear radiation in bubble chambers. Furthermore, neuroscientists are experimenting with the use of xenon in diagnostic procedures to clarify x-ray images of the human brain. NEON. Neon, of course, is best-known for its application in neon signs, which produce an eye-catching glow when lit up at night. French chemist Georges Claude (1870-1960), intrigued by Ramsay's discovery of neon, conducted experiments that led to the development of the neon light in 1910. That first neon light was simply a glass tube filled with neon gas, which glowed a bright red when charged with electricity. Claude eventually discovered that mixing other gases with neon produced different colors of light. He also experimented with variations in the shapes of glass tubes to create letters and pictures.

By the 1920s, neon light had come into vogue, and it is still popular today. Modern neon lamps are typically made of plastic rather than glass, and the range of colors is much greater than in Claude's day: not only the gas filling, but the coating inside the tube, is varied, resulting in a variety of colors from across the spectrum. Though the neon sign is its best-known application, neon is used for many other things. Neon glow lamps are often used to indicate on/off settings on electronic instrument panels, and lightweight neon lamps are found on machines ranging from computers to voltage regulators. In fact, the first practical color television, produced in 1928, used a neon tube to produce the red color in the receiver. Green came from mercury, but the blue light in that early color TV came from another noble gas, helium. HELIUM. Helium, of course, is widely known for its use in balloons—both for large airships and for the balloons that have provided joy and fun to many a small child.

Though helium is much more expensive than hydrogen as a means of providing buoyancy to airships, hydrogen is extremely flammable, and after the infamous explosion of the airship Hindenburg in 1937, helium became the preferred medium for airships. As noted earlier, the United States military made extensive use of helium-filled airships during the World War II. The use of helium for buoyancy is one of the most prominent applications of this noble gas, but far from the only one. In fact, not only have people used helium to go up in balloons, but divers use helium for going down beneath the surface of the ocean. In that situation, of course, helium is not used for providing buoyancy, but as a means of protecting against the diving-related condition known as "the bends," which occurs when nitrogen in the blood bubbles as the diver rises to the surface. Helium is mixed with oxygen in diver's air tanks because it does not dissolve in the blood as easily as nitrogen. Among the most fascinating applications of helium relate to its extraordinarily low freezing point.

Helium has played a significant role in the low-temperature science known as cryogenics, and has found application in research concerning superconductivity: the use of very low temperatures to develop materials that conduct electrical power with vastly greater efficiency than ordinary conductors. Close to absolute zero, helium transforms into a highly unusual liquid unlike any known substance, in that it has no measurable resistance to flow. This means that it could carry an electrical current hundreds of times more efficiently than a copper wire. WHERE TO LEARN MORE "The Chemistry of the Rare Gases" (Web site). < (May 13, 2001). "Homework: Science: Chemistry: Gases" Channelone.com (Web site). < (May 12, 2001). Knapp, Brian J.; David Woodroffe; David A. Hardy. Elements. Danbury, CT: Grolier Educational, 2000. Mebane, Robert C. and Thomas R. Rybolt. Air and Other Gases. Illustrations by Anni Matsick. New York : Twenty-First Century Books, 1995. "Noble Gases" Xrefer.com (Web site).

< (May 13, 2001). Rare Gases. Praxair (Web site). < (May 13, 2001). Stwertka, Albert. Superconductors: The Irresistible Future. New York: F. Watts, 1991. Taylor, Ron. Facts on Radon and Asbestos. Illustrated by Ian Moores. New York: F. Watts, 1990. Cite this article Pick a style below, and copy the text for your bibliography. MLA

Question: Which of the noble gases takes its name from the Greek for 'hidden'?
Answer: KRYPTON